How long do lice develop? - briefly
Lice finish their life cycle in roughly three weeks: eggs hatch after 7‑10 days, nymphs become adults in another 7‑10 days, and mature insects survive for about 2‑3 weeks.
How long do lice develop? - in detail
Lice progress through three distinct phases: egg, nymph, and adult.
-
Egg (nit) stage – Females deposit each egg on a hair shaft close to the scalp. Incubation requires 7–10 days at typical indoor temperatures (20‑25 °C).
-
Nymphal stage – Upon hatching, the immature insect undergoes three molts. Each molt spans roughly 2–4 days, so the entire nymphal period lasts 9–12 days. Nymphs resemble adults but are smaller and lack full reproductive capacity.
-
Adult stage – Fully formed lice become capable of mating after about a day. An adult lives approximately 30 days, during which a single female can lay 5–10 eggs per day.
Summing the phases, a complete life cycle from egg to the end of the adult’s lifespan ranges from 4 to 6 weeks. Temperature influences the timeline: higher ambient heat accelerates development, while cooler conditions extend each stage.
Species variations exist. Head lice (Pediculus humanus capitis) follow the schedule above, whereas body lice (Pediculus humanus humanus) develop slightly faster, completing the cycle in about 3 weeks under optimal conditions. Pubic lice (Pthirus pubis) have a comparable cycle, with eggs hatching in 6–9 days and adults surviving 30–40 days.
Understanding these intervals aids in timing treatment applications, ensuring that interventions target both existing insects and newly emerged nymphs before they reach reproductive maturity.